From 595dd6cffdd65d3e2bdb69f8e79c6ced441ef116 Mon Sep 17 00:00:00 2001
From: zjncs <18910855655@163.com>
Date: Fri, 4 Sep 2026 15:49:39 +0800
Subject: [PATCH] fix(repo): report the error when creating a missing merge
 index fails

When the --merge target does not exist, an empty index is created and
written before merging. The error from that write was discarded, so an
unwritable merge target let the command report success while no index
was created there. Propagate the error, matching the final index write
and the LoadIndexFile error handling in the same function.

Signed-off-by: zjncs <18910855655@163.com>
---
 pkg/cmd/repo_index.go      |  4 +++-
 pkg/cmd/repo_index_test.go | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/pkg/cmd/repo_index.go b/pkg/cmd/repo_index.go
index ece0ce811..095d9a4d7 100644
--- a/pkg/cmd/repo_index.go
+++ b/pkg/cmd/repo_index.go
@@ -101,7 +101,9 @@ func index(dir, url, mergeTo string, json bool) error {
 		var i2 *repo.IndexFile
 		if _, err := os.Stat(mergeTo); errors.Is(err, fs.ErrNotExist) {
 			i2 = repo.NewIndexFile()
-			writeIndexFile(i2, mergeTo, json)
+			if err := writeIndexFile(i2, mergeTo, json); err != nil {
+				return fmt.Errorf("merge failed: %w", err)
+			}
 		} else {
 			i2, err = repo.LoadIndexFile(mergeTo)
 			if err != nil {
diff --git a/pkg/cmd/repo_index_test.go b/pkg/cmd/repo_index_test.go
index 67984f3b7..3a31cf7a4 100644
--- a/pkg/cmd/repo_index_test.go
+++ b/pkg/cmd/repo_index_test.go
@@ -22,6 +22,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -141,3 +142,28 @@ func TestRepoIndexFileCompletion(t *testing.T) {
 	checkFileCompletion(t, "repo index", true)
 	checkFileCompletion(t, "repo index mydir", false)
 }
+
+func TestRepoIndexCmdMergeWriteError(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("directory permissions are not enforced on Windows")
+	}
+	if os.Geteuid() == 0 {
+		t.Skip("root bypasses directory permissions")
+	}
+
+	dir := t.TempDir()
+	require.NoError(t, linkOrCopy("testdata/testcharts/compressedchart-0.1.0.tgz", filepath.Join(dir, "compressedchart-0.1.0.tgz")))
+
+	// The merge target does not exist and its directory is read-only, so
+	// creating it must fail and the error must be reported.
+	roDir := filepath.Join(t.TempDir(), "ro")
+	require.NoError(t, os.Mkdir(roDir, 0o500))
+	mergeTo := filepath.Join(roDir, "index.yaml")
+
+	buf := bytes.NewBuffer(nil)
+	c := newRepoIndexCmd(buf)
+	require.NoError(t, c.ParseFlags([]string{"--merge", mergeTo}))
+
+	err := c.RunE(c, []string{dir})
+	require.Error(t, err, "expected an error when the missing merge target cannot be written")
+}